Stabilizer apparatus



April 5, 1966 G. o. SINEX 3,

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4 r Tom/E Y5 United States Patent 3,244,690 STABILIZER APPARATUS Gene 0. Sinex, Farmington, N. Mex, assignor to American Tani; and Staci Corporation, Farmington, N. Mex., a corporation of New Mexico Fitted duty 5, 1961, Ser. No. 121,978 1 Qiairn. (Cl. 196-99) This application is a continuation-in-part of a copending application of Gene 0. Sinex, Serial No. 41,414, filed July 7, 1960, now abandoned.

This invention relates to a stabilizer apparatus for hydrocarbon liquids and, more particularly, to a stabilizer apparatus including a new and improved rectifier unit.

Raw streams of liquid petroleum or multi-component hydrocarbon liquids, such as those produced by natural gas-condensate wells, crude oil wells, or natural gasoline extraction plants, usually contain varying quantities of methane, ethane, propane, butane, pentane, hexane and heavier hydrocarbon components. These components are stable in the naturally produced petroleum stream or in streams maintained under pressure during flow. However, when the hydrocarbon liquid is discharged, for instance, into a storage tank, the lighter hydrocarbon components having igher vapor pressures vaporize or flash and carry off portions of the valuable heavier components due to the stripping et'iect. These heavier components generally have a low enough vapor pressure that they could be collected in storage tanks except for the loss occasioned by the stripping effect.

in an attempt to reduce the loss of these heavier components incident to storage of the hydrocarbon liquids, a stabilizer apparatus is inserted in the line of flow between the source of the petroleum stream and the storage tank. The stabilizer permits the lighter components, such as butane and propane, to pass oil into separate storage means and recovers the heavier components in the lighter component vapors to permit the return of these heavier components to a suitable storage means. However, the present stabilizers, particularly the rectifier unit, are unduly costly in requiring an excessive amount of installation space.

Accordingly, one object of the present invention is to provide a new and improved stabilizer apparatus.

Another object is to provide a stabilizer apparatus for hydrocarbon liquids including a new and improved rectifier unit.

Another object is to provide a stabilizer apparatus including a horizontally extending rectifier unit.

A further object is to provide a stabilizer apparatus including means for separating the hydrocarbon liquid into a lighter component vapor and a heavier component residue liquid and a horizontally disposed rectifier unit for recovering the heavier components carried ofi in the vapor.

Another object is to provide a horizontally mounted rectifier unit for a stabilizing apparatus that is both small in size and economically constructed.

Another object is to provide a rectifier unit for a stabilizing apparatus including a vessel containing a horizontally extending mass of fibrous material saturated with liquefied vapor through which a lighter component vapor passes to permit the recovery of heavier components from the vapor.

Another object /is to provide a fractionating apparatus including a rectifier unit containing a contacting material through which a reflux liquid flows by gravity in a direction transverse to the flow of contacted vapors.

In accordance with these and many other objects, an embodiment of the invention comprises a reboiler to which the raw stream of liquid petroleum is supplied. The reboiler, which is maintained under specified condi- 3,244,600 Patented Apr. 5, 1956 tions of pressure and temperature, separates the lighter components as a vapor from the heavier hydrocarbon components which remain in the form of a residue liquid. The vapor from the reboiler unit is supplied to a rectifier unit comprisin an elongated and horizontally extending vessel containing a horizontally extending mass of saturable material, such as a mass of knitted glass fiber including occasional strands of stainless steel wire. The vapors passing through the mass of material in the rectifier unit are supplied to the input of a condensing means that liquefies at least a portion of the received vapors. A portion of the vapor and liquefied vapor provided at the output of the condensing means is wtihdrawn and passed through a liquid-water separator to a suitable storage means.

The remaining portion of the liquefied vapor is withdrawn from the outlet of the condensing means and supplied to a reflux accumulator. A controlled amount of the dehydrated liquid from the reflux accumulator is supplied to a horizontally extending liquid distributor disposed in the vessel of the rectifier unit immediately above the mass of material therein. This liquefied vapor saturates the mass of material so that the heavier components carried off from the reboiler unit in the vapors passing through the rectifier unit in a direction transverse to the gravity fiow of the reflux liquid are absorbed in the liquefied vapor. The liquefied vapor containing the absorbed heavier components is returned to the reboiler in which the heavier components become a portion of the residue liquid in the reboiler and the lighter components are returned to a vapor that is discharged through the rectifier unit. The residue liquid comprising the stable heavier components is withdrawn from the reboiler and forwarded to a suitable storage receptacle.

Because of the pressure drop across the rectifier unit and the condensing means, a pressure ditterential exists between the reflux accumulator and the rectifier unit that can lead to a back flow of vapor from the rectifier unit to the refiux accumulator. To prevent this back flow, one embodiment of the invention includes a U-sha ed bend in the line from the reflux accumulator to the rectifier unit to provide a liquid seal. In a second embodiment, the reflux accumulator comprises an elongated vertical tower that is positioned to provide, in efiect, the liquid seal. 1

Many other objects and advantages of the present invention will become apparent from considering the following detailed description in conjunction with the drawings in which:

FIG. 1 is a schematic diagram of a stabilizer apparatus forming a first embodiment of the invention; and

FIG. 2 is a schematic diagram of a stabilizer apparatus forming a second embodiment of the invention.

Referring now more specifically to FIG. 1 of the drawings, a stabilizer apparatus embodying the invention, which is indicated generally as 10, includes a reboiler unit 12 to which a raw stream of petroleum or multi-component hydrocarbon liquid is supplied. The reboiler unit 12 separates the received stream into a residue liquid of heavier hydrocarbon components and a vapor of lighter hydrocarbon components containing an amount of the heavier components. The vapor from the reboiler unit 12 is supplied to the inlet of a rectifier unit 14 comprising a vessel containing a horizontally extending mass of contacting material. The vapor passes through the mass of material 16 in the rectifier unit 14 and is withdrawn and forwarded to a condensing means 18 in which at least a portion of the withdrawn vapor is liquefied. A portion of the vapor and liquefied vapor is withdrawn to suitable storage means through a product accumulator 2t).

The remaining portion of the vapor and liquefied vapor is supplied from the outlet of the condensing means 18 to a reflux accumulator 22. The vapor is withdrawn from the reflux accumulator 22, and the liquefied vapor is forwarded to liquid distributing means in the rectifier unit 14 so that the mass of material 16 is saturated or filled with the liquefied vapor. This liquefied vapor absorbs the heavier components from the vapor passing through the rectifier unit 14. The liquefied vapor including the absorbed heavier hydrocarbon components is returned to the reboiler unit 12 in which the heavier components become a stable part of the residue liquid and the lighter hydrocarbon components are again flashed or vaporized to provide vapors that are discharged from the reboiler unit 12 into the rectifier unit 14.

Referring now more specifically to the detailed construction of the stabilizer apparatus 10, a raw stream of petroleum or multi-component hydrocarbon liquid is supplied to a heat exchanger 24 through an inlet or conveying means 25, and the preheated stream from this heat exchanger is supplied to an upper portion 26 of a vessel 28 forming a part of the reboiler unit 12 through a conveying means 30. The interior of the vessel 28 is maintained at a predetermined pressure by a back pressure regulator of conventional construction. This pressure can be within the range of from 70 pounds per square inch to 100 pounds per square inch when the apparatus is used with natural petroleum. If the stabilizer is used in other applications, such as in a depropanizer, the pressure can reach 250 pounds per square inch. To vaporize the feed stream, the interior of the vessel 28 is also heated to a predetermined temperature in the range of, for instance, trom 200 F. to 350 F. by a steam generator 32 that supplies steam to a coil 34 disposed within the vessel 28 through a conveying means 36 controlled by a valve 38. The steam admitted from the conveying means or line 36 into the coil 34 is controlled by adjusting the valve 38 under the control of a regulating means 40 that includes a temperature responsive element 42 disposed within the vessel 28. The condensate from the coil 34 is returned to the steam generator 32 through a line 44.

In dependence on the conditions of pressure and temperature maintained in the vessel 28, the multicomponent hydrocarbon liquid discharged into the vessel 28 from the inlet line 30 is separated into a residue liquid of heavier hydrocarbon components disposed in a lower portion 46 of the vessel and a vapor of lighter hydrocarbon components carrying portions of the heavier components that is collected in the upper portion 26 of the vessel 28. The separation of the liquid and vapor phases of the raw stream is facilitated by a plurality of partitions or plates 48, 50 and 52 that are disposed within and extend transversely across the vessel 28.

The reboiler unit 12 also includes a means for separating water from the incoming hydrocarbon liquid. This water separating means comprises a depending cylindrical portion 28a formed at one end of the vessel 28 in which a cylinder 54 is disposed in spaced concentric relation. An outlet pipe 56 is disposed within the cylinder 54 and is provided with an open upper end located at the level at which the water is to be withdrawn. The lower end of the pipe 56 is connected to a float controlled valve assembly 58 that controls the discharge of separated water to an outlet line 60.

The reboiler unit 12 also includes means for withdrawing the residue liquid from the lower portion 46 of the vessel 28. This means comprises an outlet portion 62 formed in one end of the vessel 28 by a weir consisting of the partitions 50 and 52. A lower end of the portion 62 is connected to a valve 64. The outlet valve 64 is controlled by a regulating means 66 including a level respon sive or float controlled element 68 disposed within the outlet portion 62 of the interior of the vessel 28. The warmed residue liquid discharged from the vessel 28 through the valve 64 is conveyed by a line 70 to the input 4 of the heat exchanger 24. The outlet of the heat exchanger 24 is connected by a line 72 to a suitable storage means for the heavier hydrocarbon components. Since the residue liquid is heated in the reboiler unit 12, the flow of this fluid through the heat exchanger 24 serves to preheat the raw stream of multi-component hydrocarbon liquid passing through the lines 25 and 30 to the reboiler unit 12.

The rectifier unit 14 includes an elongated and horizontally mounted vessel or cylinder 74 including a lower inlet that is placed in communication with the upper portion 26 of the vessel 28 by a conveying means or line 76. The vessel 74 also includes an upper outlet means which is horizontally spaced from the inlet means and which is connected to a line 78. The interior of the vessel 74 between the inlet and outlet means is filled with the mass of contacting material 16 that is saturated by the liquefied vapor supplied by the reflux accumulator 22. In a preferred construction, the mass of fibrous, vapor contacting material 16 comprises knitted glass fibers including occasional strands of stainless steel wire. The material 16 possesses the characteristics of being saturated with the liquefied vapor supplied by the reflux accumulator 22 or of dispersing this liquefied vapor into a large vapor contacting surface while freely passing liquid and vapor in separate movements. In order to distribute the liquefied vapor supplied by the reflux accumlator 22, a distributing chamber formed by a wall of the vessel 74 and an apertured plate or structure 82 is provided. The distributing chamber 80 is supplied with the liquefied vapor from the reflux accumulator 22, and this liquid flows into the mass of material 16 through the plurality of apertures in the structure 82. These openings or apertures are disposed above and extended substantially along the full length of the mass of material 16. In one rectifier unit 14 embodying the present invention, the vessel 74 comprises a cylinder that is eight inches in diameter and thirty inches long. This horizontal rectifier unit has approximately the same processing capacity as a vertical tower that is one foot in diameter and twenty feet high.

The condensing means to which the vapor passing through the line 78 is conveyed comprises a unitary input header 84 that is connected to an output header 86 by a plurality of finned tubes 88 in which the vapor is at least partially liquefied. The output header 86 is divided into a plurality of segments or sectors by a plurality of valves 90. This permits the vapor and liquid discharged from the tubes 88 to be discharged in controlled quantities through a line .92 to the product accumulator 20 or through a line 94 to the reflux accumulator 22. The condensing means 18 cools the incoming vapors to approximately ambient temperature so that the resulting condensate or liquefied vapor consists largely of butane and propane under normal operating conditions.

A portion of the liquefied vapor or condensate provided at the output header 86, as determined by the adjustments of the valves 90, is supplied over the line 92 to the product accumulator 20. This accumulator comprises a vessel 96 divided by a partition 98. A back pressure regulator 10!? that is connected to the upper end of the vessel 96 by a line 102 serves to maintain a suitable back pressure in the system, including a reboiler 26,

and provides a means for withdrawing vapors that accumulate in the upper portion of the vessel 96. The partition 98 provides means by which the liquefied vapor supplied to the vessel 96 is separated from water. The water accumulates in the lower portion of vessel 96 and in the portion of the interior to the right of the partition 98. The accumulated water is discharged from the vessel 96 through the line 104 and a level response or float controlled valve assembly 106. The portion of the interior of the vessel 96 disposed to the left of the partition 98 collects the liquefied vapor which overflows through an outlet pipe 108 to a level responsive or float controlled valve assembly 110. The valve assembly 110 discharges the liquefied vapor comprising the lighter components of the raw stream of hydrocarbon liquid into a suitable storage means therefor.

As indicated above, the line 94 supplies the remaining portion of the liquefied vapor from the condensing means 18 to the reflux accumulator 22. This reflux accumulator includes a vessel 112 that is divided into two portions by a partition 114. The upper end of the interior of the vessel 112 is placed in communication with the back pressure regulator 100 through a line 116. This provides means for maintaining a suitable back pressure on the system and for removing vapors accumulating in the upper portion of the vessel 112. The partition 114 provides a means by which any water in the stream entering the reflux accumulator 22 can be removed. The lower portion of the vessel 112 and the portion disposed to the right of the partition 114 collects the water, and the collected water overflows into an outlet pipe 118. The pipe 118 can either discharge the water directly or supply the separated water to the line 92 leading to the input of the product accumulator 20. The liquefied vapor accumulates in the portion of the interior of the vessel 112 disposed to the left of the partition 114 and overflows through an outlet line 120 that is connected to the distributing chamber 80 in the rectifier unit 14. Thus, the selected portion of the liquefied vapor enters the distributing chamber 30 and passes through the apertures in the structure 82 to saturate the mass of fibrous material 16.

Because of the pressure drop across the rectifier unit 14 and the condensing means 18, there is a possibility that a back flow of vapor from the rectifier unit 14 to the reflux accumulator 22 may occur. To prevent this, the outlet line 120 is provided with a U-shaped portion 120a that forms a U-tube liquid seal between the rectifier unit 14 and the reflux accumulator 22.

When the stabilizer apparatus is placed in operation, the back pressure regulators for the system are adjusted to a proper setting, and the regulating means 40 is adjusted so that the interior of the vessel 28 rises to the desired temperature. When a raw stream of liquid petroleum or multi-component hydrocarbon liquid is supplied to the inlet line 25, this liquid is preheated in the heat exchanger 24 by the heated residue liquid passing through the line 70 and 72, and the preheated liquid is discharged from the line 30 into the upper portion 26 of the vessel 28.

The temperature and pressure maintained within the vessel 28 causes the heavier hydrocarbon components of the liquid to settle as a residue liquid in the lower portion 46 of the vessel 28 while the lighter hydrocarbon components vaporize or flash into a vapor containing portions of the heavier components, which vapor collects in the upper portion 26 of the vessel 28. This vapor passes through the conveying means 76 to the inlet of the vessel 74 and then passes through the fibrous material 16 which is saturated with the liquefied vapor returned from the reflux accumulator 22. The liquefied vapor in the material 16 absorbs the heavier hydrocarbon components carried by the lighter component vapor, and the liquefied vapor together with the heavier components absorbed therein flows downwardly through the conveying means 76 into the interior of the vessel 28. The heavier components are returned to a stable state in the residue liquid provided in the lower portion 46 of the vessel 28. This residue liquid flows through the weir to the outlet portion 62 from which it is discharged under the control of the level responsive valve 64 through the line 70, the heat exchanger 24, and the line 72 to a suitable storage means.

The vapor passing through the material 16 in the vessel 74 fiows through the line 78 to the inlet header 84 in the condensing means 18. This vapor passes through the finned tubes 88 and is cooled to ambient temperature so that a condensate or liquefied vapor including the lighter hydrocarbon components, such as butane and propane, is

provided in the segmented outlet header 86. The portion of the liquefied vapor in the outlet header 86 determined by the settings of the valves 90 is conveyed through the line 92 to the product accumulator 20 in which any water is separated and discharged through the valve assembly 106. The liquefied vapor is separately collected and discharged through the valve assembly to suitable storage means therefor.

The remaining portion of the liquefied vapor passes through the line '94 to the reflux accumulator 22 in which the water is separated and discharged through the line 118 to the pro-duct accumulator 20. The separated liquefied vapor is forwarded from the reflux accumulator 22 through the line 120 to the distributing chamber 80 in the rectifier unit 14. This liquefied vapor saturates the mass of fibrous material 16 to provide a reflux liquid for absorbing heavier hydrocarbon components from the vapor supplied from the reboiler unit 12 to the rectifier unit 14. As indicated above, the liquefied vapor and the heavier hydrocarbon components absorbed therein are returned to the reboiler unit 12 through the conveying means 76. Thus, the apparatus 10 embodies means by which the reflux liquid moves by gravity through the contacting material 16 in a direction transverse to the flow of the vapor from the reboiler 12 to provide efficient and compact means for removing the heavier hydrocarbon components.

Referring now more specifically to FIG. 2 of the drawings, therein is shown a stabilizer apparatus, indicated generally as 121, which embodies the invention and which is substantially identical to the stabilizer apparatus 10 except for the means for diverting a portion of the liquefied vapor to the rectifier unit. To illustrate the similarities of the stabilizer units 10 and 121, a reference number identifying a part in FIG. 1 is used to designate an identical part in FIG. 2 with a prime added.

In general, the heat supplied by the steam generator 32' to the reboiler 12' vaporizes the lighter components of the raw feed stream, and this vapor passes through the rectifier unit 14' to the condensing means 18. The condensing means 18' supplies a mixture of vapor and liquefied vapor to an output header 122 in which it is collected and conveyed over a line 124 to the upper end of a reflux accumulator 126.

The reflux accumulator 126 comprises a vertically extending column or vessel 128 in which a partition 130 is disposed. The vapors supplied by the line 124 are collected in the upper end of the vessel 128 and conveyed over a line 132 to a fuel gas drip unit 134. The unit 134 provides additional means for separating vapor and liquefied vapor and for withdrawing vapor and liquefied vapor from the apparatus 121. The unit 134 includes a vapor outlet 136 connected to a back pressure regulator 140 that maintains a suitable back pressure in the apparatus 121 including the reboiler 12'. A second or liquid outlet 142 is connected between the fuel gas drip unit 134 and the valve assembly 110 through which liquefied vapors are discharged from the apparatus 121. The line 132 is also connected to the product accumulator 21) to provide means for withdrawing vapor from this unit.

The partition 130 within the vessel 128 provides means for separating liquefied vapors discharged from the condensing means 18' from any water included in the discharge stream from the condensing means 18'. This water overflows into the upper end of a line 144 and is discharged into the product accumulator 20 in which the stream is again separated into vapors discharged to the fuel gas drip unit 134, into water that is discharged by the valve assembly 106, and into liquefied vapor which is discharged through the valve assembly 110.

The liquefied vapors disposed in the outer portion of the vessel 128 are conveyed to the distributing chamber 80' of the rectifier unit 14' through a line 146 that is connected to the vessel at a point above the liquefied vaporwater interface. A flow control and indicator unit 148 is interposed in the line 146 to provide means for controlling the rate at which the reflux liquid or liquefied vapor is withdrawn from the reflux accumulator 126 and returned to the rectifier unit 14'. Further, since the point of discharge from the line 146 into the distributing chamber 80 is disposed below the upper level of the liquefied vapor in the vessel 128 and above the point of withdrawal from the vessel 128, this vessel and the line 146 including the flow control unit 148 provide a U-tube liquid seal to prevent any back flow of vapor from the rectifier unit 14' to the reflux accumulator 126 due to any pressure differential existing in the system because of pressure drops in the rectifier unit 14' and the condensing means 18'.

The flow control unit 148 is adjusted so that sufficient liquified vapor flows from the refiux accumulator 126 to saturate the packing material 16'. The reflux liquid or liquefied vapor flows solely by gravity from the reflux accumulator 126 through the contacting material 16 in a direction transverse to the flow of vapor through the rectifier 14 from the reboiler 12' to the condensing means 18'. Thus, the heavier hydrocarbon components in the vapor supplied by the reboiler unit 12' are absorbed by liquid contact with the transversely flowing liquefied vapor saturating the packing material 16' to provide an efiicient and compact means for returning these heavier hydrocarbon components to the reboiler unit.

Although the present invention has been described with reference to two embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

A stabilizer apparatus for use with a multicomponent hydrocarbon liquid comprising a first vessel supplied with said liquid for separating lighter components of said liquid as a vapor from the heavier components of said liquid, at second horizontally extending vessel having an inlet means and an outlet means spaced horizontally from said inlet means, a mass of inert, fibrous material in said second vessel disposed between said inlet means and said outlet means and providing a vapor contacting surface of large area, the vapor flowing through the mass of material in a horizontal direction to provide an elongated and horizontally extending vapor flow path through the mass of material in intimate contact with the vapor contacting surface of the mass of material, means for supplying said vapor to said inlet means, means supplied with vapor from said outlet means for liquifying at least a portion of said vapor, a horizontally extending liquid distributor disposed in said second vessel above and in communication with said mass of fibrous material through elongated and horizontally extending opening means, and means for returning at least a portion of said liquified vapor to said liquid distributing means to pass over said fibrous material by gravity in a direction transverse to the flow of vapor, the returned liquified vapor being filmed on the vapor contacting surface to absorb the heavier components of the vapor in said second vessel, said liquified vapor and the heavier components absorbed therein being returned from said second vessel to said first vessel.

References Cited by the Examiner UNITED STATES PATENTS 1,759,814 5/1930 Gray 19698 1,769,788 7/1930 Leamon 196-98 1,780,977 11/1930 Leslie et al. 208358 1,804,917 5/1931 Deppe et a1. 208--106 1,962,752 6/ 1934 Stratford 208358 2,071,909 2/1937 Watt 208358 2,170,180 8/1939 Youker 208-261 2,598,684 6/1952 Goldblatt et a1 20246 2,707,163 4/1955 Thibaut 196-98 2,805,981 9/1957 Cavin et al. 208352 2,952,631 9/1960 Hausch 208-358 DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, JAMES S. BAILEY,

Examiners. 

